Fast heat-up of a thermal conditioning device E.G. for coffee machine

ABSTRACT

The invention concerns a unit ( 1000 ) for controlling transmission of power to a thermal conditioning device ( 100 ) e.g. for coffee machine, comprising a controller ( 2 ) with a start-up profile for starting-up said device ( 100 ) from a temperature of inactivity (TI) to an operative temperature for bringing to a target temperature (TT) a fluid circulating through said device ( 100 ) at start-up end, said controller ( 2 ) being arranged to allow circulation of fluid through said device ( 100 ) at start-up end and to compare the determined temperature (SOT) of fluid circulated at start-up end to the target temperature (TT) and derive a temperature difference therefrom. It is characterized in that the start-up profile has at least one parameter and in that said controller ( 2 ) has a self-learning mode for adjusting said parameter as a function of said temperature difference and to store the adjusted parameter for a subsequent starting-up of said device ( 100 ). The invention concerns in particular a method for optimized heating up of a coffee machine ( 104 ).

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a National Stage of International ApplicationNo. PCT/EP2011/059771, filed on Jun. 14, 2011, which claims priority toEuropean Patent Application No. 10166366.4, filed on Jun. 17, 2010, theentire contents of which are being incorporated herein by reference.

FIELD OF THE INVENTION

The invention concerns the start-up of a thermal conditioning device, inparticular a device with a thermal accumulator such as a thermoblock,for heating or cooling a fluid circulating therethrough, e.g. a heaterfor a beverage preparation machine. In particular the present inventionconcerns a method for optimized heating up of a coffee machine in-lineheater to an operating temperature from a rest temperature with bestpossible heat up time and consideration of different systemconstellations.

For the purpose of the present description, a “beverage” is meant toinclude any liquid food, such as tea, coffee, hot or cold chocolate,milk, soup, baby food or the like. A “capsule” is meant to include anypre-portioned beverage ingredient within an enclosing packaging of anymaterial, in particular an air tight packaging, e. g. plastic, aluminum,recyclable and/or bio-degradable packaging and of any shape andstructure, including soft pods or rigid cartridges containing theingredient.

BACKGROUND ART

Beverage preparation machines have been known for a number of years. Forexample, U.S. Pat. No. 5,943,472 discloses a water circulation systembetween a water reservoir and a hot water or vapour distribution chamberof an espresso machine. The circulation system includes a valve,metallic heating tube and pump that are connected together and to thereservoir via different silicone hoses, which are joined using clampingcollars.

EP 1 646 305 discloses a beverage preparation machine with a heatingdevice that heats circulating water which is then supplied to the inletof a brewing unit. The brewing unit is arranged to pass heated water toa capsule containing a beverage ingredient for its brewing. The brewingunit has a chamber delimited by a first part and a second part movablerelative to the first part and a guide for positioning a capsule in anintermediate position between the first and second parts before movingthe first and second parts together from an open to a closedconfiguration of the brewing unit.

In-line heaters for heating circulating liquid, in particular water arealso well known and are for example disclosed in CH 593 044, DE 103 22034, DE 197 32 414, DE 197 37 694, EP 0 485 211, EP 1 380 243, FR 2 799630, U.S. Pat. No. 4,242,568, U.S. Pat. No. 4,595,131, U.S. Pat. No.5,019,690, U.S. Pat. No. 5,392,694, U.S. Pat. No. 5,943,472, U.S. Pat.No. 6,393,967, U.S. Pat. No. 6,889,598, U.S. Pat. No. 7,286,752, WO01/54551 and WO 2004/006742.

More particularly, CH 593 044 and U.S. Pat. No. 4,242,568 disclose acoffee machine with an inline thermoblock heater having a metal masswith a resistive heating cable cast in the mass and with a duct for thecirculation of water to be heated.

Thermoblocks are in-line heaters through which a liquid is circulatedfor heating. They generally comprise a heating chamber, such as one ormore ducts, in particular made of steel, extending through a mass ofmetal, in particular a massive mass of metal, in particular made ofaluminium, iron and/or another metal or an alloy, that has a highthermal capacity for accumulating heat energy and a high thermalconductivity for the transfer the required amount of the accumulatedheat to liquid circulating therethrough whenever needed. Instead of adistinct duct, the thermoblock's duct may by a through passage that ismachined or otherwise formed in the duct's body, e.g. formed during acasting step of the thermoblock's mass. When the thermoblock's mass ismade of aluminium, it is preferred, for health considerations, toprovide a separate duct, for example of steel, to avoid contact betweencirculating liquid and aluminium. The block's mass can be made of one orseveral assembled parts around the duct. Thermoblocks usually includeone or more resistive heating elements, for instance discrete orintegrated resistors, that convert electrical energy into heatingenergy. Such resistive heating elements are typically in or on thethermoblock's mass at a distance of more than 1 mm, in particular 2 to50 mm or 5 to 30 mm, from the duct. The heat is supplied to thethermoblock's mass and via the mass to the circulating liquid. Theheating elements may be cast or housed into the metal mass or fixedagainst the surface of the metal mass. The duct or ducts may have ahelicoidal or another arrangement along the thermoblock to maximiseits/their length and heat transfer through the block.

A drawback of thermoblocks lies in the difficulty to accurately controlthe temperature and optimise the required heating energy for bringingthe liquid to be heated to the desired temperature. Indeed, the thermalinertia of the metal mass, the localised and uneven resistive heating ofthe mass, the dynamic heat diffusion from the heating in the mass todifferent parts of the mass affecting the measured temperature of themass at predetermined locations make an accurate control of thethermoblocks to heat the circulating liquid to a desired predeterminedtemperature quite difficult and moreover requires quite long pre-heatingperiods, typically of 1 to 2 min in the case of espresso machines.Furthermore, it is difficult to predict various parameters involving thesubsequent use of the thermoblock produced in series, e.g. thetemperature of the environment, the net voltage of the mains, the actualvalue of the heating resistor of the thermoblock, thermal insulation ofthe thermoblock, the initial temperature of the liquid circulatedthrough the thermoblock. Consequently, thermoblocks are usuallyassociated with dynamic loop-controlled powering circuit tailoring thepowering of the thermoblock with continuous measuring of the temperatureby means of at least one temperature sensor. However, due to the complexthermal flow of such a system, the stabilisation of the thermoblock at acertain temperature level adjusted to the real heating needs of the flowof liquid to be circulated is lengthy and still difficult to achieve.

An approach to improve the heating accuracy is taught in EP 1 380 243.This patent discloses a heating device intended in particular to equipcoffee machines. This heating device comprises a metal tube throughwhich the liquid that is to be heated can flow from an inlet duct to anoutlet duct. The exterior surface of the tube is covered over severalsections of its length with a plurality of sets of electric resistiveelements in series. A cylindrical insert extends inside the tube toform, with the interior wall of the tube, a helical duct through whichthe liquid can circulate and which thus encourages turbulent flow andrapid transfer of energy from the tube to the liquid. A flowmeter isalso positioned upstream of the inlet duct. The device further comprisesa plurality of temperature sensors distributed along the length of thetube at the entry to and exit from each set of resistive elements. Theprinciple governing the distribution of heating energy to the liquid inthis instance is based on modulating the electrical power produced bythe resistive elements which can be switched independently of oneanother or in series according to the water temperature at the inlet tothe duct. Although this device gives results which are satisfactory interms of the speed of heating, this device is relatively bulky in thatthe volume of water to be heated determines the height of the tube, andis expensive in that it requires resistive elements to be printed in theform of thick films on the surface of the tube, using what is currentlyknown as “thick film” technology.

Furthermore, the accuracy with which the liquid temperature is regulatedis limited by the fact that the liquid does not come into direct contactwith the sensors which are positioned outside the tube. The rate ofresponse to temperature differences, due to the inertia of the liquidthat is to be heated, is also slower, and this detracts from theaccuracy with which the temperature can be regulated. It should also benoted that the proximity of the temperature sensors to the sets ofresistive elements runs the risk of influencing the measurement in anuncontrollable manner because of the thermal conduction that occursthrough the wall of the tube.

In addition, more or less complex attempts to improve the thermalcontrol of heaters for batch or in-line low inertia heaters have beenproposed in DE 197 11 291, EP 1 634 520, U.S. Pat. No. 4,700,052 andU.S. Pat. No. 6,246,831.

Other methods for controlling heaters are known from different documentslike WO2008/023132, which describes an evaluation of the system heat upspeed and calculation of needed energy, but which is mostly based torelay technology and different water content of the heater, like a watercooker.

EP 0 935 938 B1 shows how an automatic start of a pump after heat uptarget is reached, and concerns in general measuring of temperature witha resistance based temperature sensor to monitor temperature of aheater. Different heat up cut-off temperatures are contemplated for theheater depending on the temperature of the heater at powering thereof.

There is still a need to provide a simple and reliable power control forthermoblocks for a fast heating thereof for accurately heating a liquidcirculated there through during normal use and under various conditionsof use.

SUMMARY OF THE INVENTION

A preferred object of the invention is to provide an in-lineself-learning heating device with a heat accumulator, such as athermoblock, that has a minimum start-up duration to reach a sufficienttemperature for initiating a first beverage preparation.

In order to provide such a self-learning heating device the inventionendeavours to develop a self-learning control system easy to integratein this heating device.

Thus the present invention concerns a self-learning heating device witha thermoblock and a self-learning controller, particularly for abeverage preparation machine, more particularly for a coffee machine.Said beverage preparation machine or coffee machine includes at leastone such self-learning heating device.

A preferred object of the invention is to provide a method for optimizedheating up of an electrical device, particularly of such a beveragepreparation machine, particularly of a coffee machine, to an operatingtemperature from any starting temperature with best possible heat uptime.

The pre-heating process is configured with the idea that a givenbeverage preparation machine will generally start-up under the same orsimilar conditions every time it is started after an extend period ofnon-use, e.g. from a “cold” state.

Once the machine is installed in a location, such as kitchen, theexternal conditions, such as the surrounding temperature, e.g. the roomtemperature and net voltage will normally not vary significantly or atleast not radically over time. Moreover, the internal characteristics ofa given heating device, in particular the electric heating element orresistor of the thermoblock will not significantly change over timeeither.

The complete heating process is so configured that a given beveragepreparation machine can start-up under any conditions, or from a coldstate, or after other beverage preparations. The speed of the heatingprocess according the invention has to be optimized independently of thelocation of the beverage preparation machine, or of the climaticconditions, or of the features of the local electric current, or ofother intern or extern parameters.

With each start-up of the machine, a temperature sensor system willmonitor the temperature of the circulated water supplied by the heaterand adjust, if necessary, the preheating duration for the next start-upprocedure, and the heating process in order to reach as close aspossible a given target temperature, e.g. for coffee extraction, such asin the range of 85 to 95° C. as appropriate.

It follows that the machine has a self-learning pre-heating or/andheating process that improves over time by learning in a givenenvironment. In practice, one or two start-up procedures may besufficient to fine-tune the machine to the specific internal andexternal conditions under which it is operating.

If the machine is moved to a different location, e.g. in an environmentthat is hotter or cooler, the self-learning preheating process will haveto re-adapt to the new environment. Equally, if the machine is repairedin a manner that affect the heating characteristics, e.g. a resistiveheater is replaced by a new one that does not have exactly the sameheating characteristics, the machine will need to undergo a newself-learning process.

Each time the conditions of start-up are significantly changed, themachine will have to readjust and the temperature of the first beveragewill be slightly substandard.

Consequently, the heater control for preheating will be adjusted toallow beverage preparation as soon as the heater is in a state, derivedexperimentally from past start-ups with the same heater, to heat to thedesired temperature the required amount of circulated liquid.

The present invention thus departs from the prior art approach ofproviding an average setting for the preheating supposed to be more orless adapted to any contemplated operating conditions, and then adjustthe preheating in the course of each preheating cycle to take intoaccount the real operating conditions. The present invention provides apreheating resetting system to align the preheating setting to theactual operating conditions which are expected to be more or lessconstant over time so that no or minimal fine-tuning is needed duringeach preheating cycle. In other words, instead of readjusting thepreheating during the preheating in a time and/or energy consumingprocess, the system of the invention is adapted to anticipate thepreheating requirements derived from the experienced conditions of aparticular machine with its particular characteristics and operating ina particular environment. The machine is arranged to adapt itself to itsoperating conditions and optimise the start-up procedure accordingly.

For an espresso machine, e.g. typically with a heater of about 1200 Wfor heating up 25 to 130 ml in about 10 to 40 sec., it has been observedthat by relying on past experimental pre-heating experience instead of apreheating based on a loop controlled preheating process, temperaturesensing issues in the heater relating to a temperature gradientthroughout the heater may be avoided and the pre-heating duration may bereduced by 30 to 70%, e.g. from 90 sec to 30 sec or less.

Consequently, the heater control for heating can be adjusted generallyto allow beverage preparation as soon as physically possible.

Therefore, the present invention relates to a unit for controllingtransmission of power to a thermal conditioning device, such a heater orcooler. This unit comprises:

-   -   a controller with a start-up profile for starting-up such a        thermal conditioning device from a temperature of inactivity to        an operative temperature for bringing to a target temperature a        fluid circulating through said thermal conditioning device at        start-up end; and    -   a temperature sensor connected to said controller for        determining a temperature of said fluid upon circulation through        said thermal conditioning device.

The controller is arranged to allow circulation of fluid through thethermal conditioning device at start-up end and to compare thedetermined temperature of fluid circulated at start-up end to the targettemperature and derive a temperature difference therefrom.

In accordance with the invention, the start-up profile has at least oneparameter and the controller has a self-learning mode for adjusting suchparameter as a function of said temperature difference and to store theadjusted parameter or parameters for a subsequent starting-up of saidthermal device.

At least one parameter can be a duration of the power start-up profile.At least one parameter may be a power intensity of the power start-upprofile. In any case, the power intensity may be variable or constantover time during start-up. For example, at least one parameter is atarget temperature of said thermal conditioning device.

The thermal conditioning device typically comprises a thermalaccumulator or a thermoblock.

In an embodiment, said controller includes at least a clock to launchmeasures of temperature at periodic time intervals, and includes datastorage means for storing a target temperature and for storingtemperatures measured at said periodic time intervals, and saidcontroller further including calculation means for calculating aswitch-off temperature, said calculation means being arranged for:

-   -   a) calculating temperature gradients between different stored        temperatures values;    -   b) calculating an average gradient of said temperature        gradients; and    -   c) calculating a switch-off temperature by subtracting an        overshoot temperature to said target temperature, said overshoot        temperature corresponding to said average gradient by means of a        calculation from said last calculated average gradient, or by        means of a correlation with store conversion tables between said        average gradients and overshoot temperatures,

the data storage means being further arranged for storing:

-   -   A) said overshoot temperature;    -   B) said calculated temperature gradients;    -   C) said calculated average gradient; and    -   D) said calculated switch-off temperature,

the controller device being arranged for switching off the thermalconditioning device when the last measured temperature overshoots saidcalculated switch-off temperature.

The invention still concerns a heating device for, and arranged to beincorporated into, a beverage preparation machine or a coffee machine,including at least such one unit. Typically, the heating device has apowering in the range of 0.5 to 3 kW and an ability to heat up acirculating fluid for preparing one or two beverage cups, e.g. byheating 25 to 300 ml water from room temperature to around 80 to 90° C.,in 5 to 50 sec.

The invention also concerns a beverage preparation machine, such as acoffee machine, including at least such a self-learning heating device.

A further aspect of the invention concerns a method for optimizedheating up of a beverage preparation machine, such as a coffee machine,to an operating temperature from any starting temperature with bestpossible heat up time and consideration of different systemconstellations, like namely:

-   -   net voltage tolerances, for example from nominal voltage, e.g.        110 or 220 V, up to +/−20%;    -   heat resistance tolerances, for example +/−10%,    -   different environmental temperatures, for example in the range        of 5° C. to 40° C.;    -   different thermal isolation of heater, which entails different        temperature losses, for example +/−5%;    -   different heater starting temperatures, for example 5° C. to 90°        C.;    -   heating device either full of water or empty.

Thus the invention concerns a method for optimized heating up of abeverage preparation machine, such as a coffee machine, to an operatingtemperature from any starting temperature with best possible heat uptime, said machine, e.g. coffee machine, including an unit forcontrolling transmission of power to a thermal conditioning device, sucha heater or cooler, said unit comprising:

-   -   a controller with a start-up profile for starting-up such a        thermal conditioning device from a temperature of inactivity to        an operative temperature for bringing to a target temperature a        fluid circulating through said thermal conditioning device at        start-up end; and    -   a temperature sensor connected or included to said controller        for determining a temperature of said fluid upon circulation        through said thermal conditioning device,

where said controller includes at least a clock to launch measures oftemperature at periodic time intervals, and includes data storage meansfor storing a target temperature and for storing temperatures measuredat said periodic time intervals, and said controller further includingcalculation means for calculating a switch-off temperature,characterized in that:

-   -   a) said clock triggers at each time interval a measure of        temperature;    -   b) said measured temperatures are stored one after another in a        stack memory included in said data storage means;    -   c) said calculation means calculate temperature gradients        between some of said stored temperatures values;    -   d) said calculation means calculate an average gradient of said        temperature gradients;    -   e) said calculation means calculate a switch-off temperature by        subtracting an overshoot temperature to said target temperature,        said overshoot temperature corresponding to said average        gradient by means of a calculation from said last calculated        average gradient, or by means of a correlation with store        conversion tables between said average gradients and overshoot        temperatures,    -   f) said controller device switches off said thermal conditioning        device when the last measured temperature overshoots said        calculated switch-off temperature.

Other exemplary features of the invention are disclosed in the followingdescription.

A system index can be defined during each heat up that fulfils certaincriteria. This index is written to a permanent memory, e.g. an EEPROM.Repeated heat up cycles allow the system to adapt to the actualoperating constraints.

The heat up algorithm typically depends on the system index and allowsan accurate forecast of the needed heat energy to bring the heatingsystem to target temperature in the shortest possible time.

The pre-heating and the start-up are adapted to the machine itself andto its particular environment of use. The controller controls thethermal answer of the thermal conditioning device, particularly of theheating device, before powering. In particular, the controller processestemperature measures of the thermal conditioning and controls thetemperature conditioning accordingly. The invention thus allows anadaptive, self-learning, control of heating with the shortest possibleheat up time.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described with reference to the schematicdrawings, wherein:

FIG. 1 shows a heating device according to the invention incorporating athermoblock with a self-learning controller;

FIG. 2 illustrates a fluid circulation in a similar thermoblock;

FIG. 3 shows a temperature/time diagram according to the invention; and

FIG. 4 shows a logic diagram of a process according to the invention.

DETAILED DESCRIPTION

The following description of exemplary embodiments according to theinvention related to electrical devices for the preparation ofbeverages.

FIG. 1 shows a unit 1000 for controlling transmission of power to athermal conditioning device 100, such a heater or cooler, said unit 1000comprising:

-   -   a controller 2 with a start-up profile for starting-up such a        thermal conditioning device 100 from a temperature of inactivity        TI to an operative temperature for bringing to a target        temperature TT a fluid circulating through said thermal        conditioning device 100 at start-up end; and    -   a temperature sensor 70 connected to said controller 2 for        determining a temperature of said fluid upon circulation through        said thermal conditioning device 100.

This controller 2 is arranged to allow circulation of fluid through thisthermal conditioning device 100 at start-up end and to compare thedetermined temperature SOT of fluid circulated at start-up end to thetarget temperature TT and derive a temperature difference therefrom.

According the invention, the start-up profile has at least oneparameter, and this controller 2 has a self-learning mode for adjustingthis at least one parameter as a function of this temperature differenceand to store the adjusted parameter or parameters for a subsequentstarting-up of this thermal device 100.

According the invention, this parameter of the start-up profile can be,preferably but not restrictively:

-   -   a duration of the power start-up profile;    -   a power intensity of the power start-up profile;    -   a target temperature TT of said thermal conditioning device 100.

A detailed example of such a start-up profile will be presented furtherin the description of the invention.

This thermal conditioning device 100 may have a thermal accumulator or athermoblock.

Hereafter is described a preferred realisation for a thermalconditioning device 100, such a heater or cooler, for a beveragepreparation machine, particularly a coffee machine 104.

FIG. 1 shows an exploded view of a thermal conditioning device 100, alsosaid heater, of a beverage preparation machine only partially shown onthe figures, particularly a coffee machine 104 only partially shown onthe figures, in which liquid is circulated through a thermoblock 101 andthen guided into a brewing chamber 200 for brewing a beverage ingredientsupplied into the brewing chamber 200. An example of such a beveragemachine is disclosed in WO 2009/130099, the content of which is herebyincorporated by way of reference.

For instance, a beverage ingredient is supplied to the beveragepreparation machine, particularly the coffee machine 104, in a capsule.Typically, this type of beverage machine is suitable to prepare coffeeand is in this case called a coffee machine 104, or to prepare teaand/or other hot beverages or even soups and like food preparations. Thepressure of the liquid circulated to the brewing chamber 200 may forinstance reach about 2 to 25 bar, in particular 5 to 20 bar such as 10to 15 bar.

The thermal conditioning device 100 shown in FIG. 1 has a thermoblock101 with an aluminium metal mass 1 and a controller 2 like a functionalblock including a thermal and electrically insulating plastic housing 3containing a printed circuit board 4, e.g. bearing one or morecontrollers, memory devices, and similar, which are detailed hereafter.According to the invention, said controller 2 is a self-learningcontroller.

Metal mass 1 incorporates a water inlet, a water outlet and a waterheating duct extending there between to form a free-flow passage notshown on the figures for guiding water circulating from a waterreservoir via a pump not shown on the figures through metal mass 1.

As illustrated in FIG. 2 a thermoblock's mass 1 may include a heatingduct 12. Heating duct 12 has an inlet 12A and an outlet 12B.

Heating duct 12 may extend helicoidally through mass 1 and in particularalong a generally horizontal axis. Duct 12 may have upper flow portionsfollowed by a down-coming flow portions. Such upper flow and down-comingflow portions of duct 12 may have a narrowed cross-section for promotingan increased velocity of water therealong to inhibit an accumulation ofbubbles in such upper flow portion by pushing them down the down-comingflow portion by the flow of water with increased velocity. In thisconfiguration, the duct is arranged so that the size of itscross-section changes along the chamber, to increase the flow velocityin areas, usually upper areas, which might otherwise serve to capturebubbles, in particular vapor bubbles. The increased liquid velocity inthese areas “washes” all possible bubbles away from these areas with thefast flow of liquid in these areas. To avoid overheating in such areaswith reduced cross-section, the heating power may be reduced on thecorresponding parts of the heater, for instance, by adjusting theresistive means on these parts. In a variation, this duct has a reducedcross-section along its entire length to provide a sufficient velocityof the water flow for flushing possible vapour bubbles formed thereinduring heating. The heating duct 12 may be provided with differentsections to influence the flow so that the thermal transfer is moreevenly distributed and prevents local overheating and resulting bubbleformation.

As illustrated in FIG. 1, metal mass 1 of the thermoblock 101 furtherincludes an opening 1B which forms or rigidly anchors an upstream partof the brewing chamber 200 only partially shown on the figures so thatthe rigid passage of metal mass 1 extends into the brewing chamber 200.The beverage preparation machine or coffee machine 104 also comprises adownstream part not shown on the figures having a beverage outlet andcooperating with the upstream part to form the brewing chamber 200, thedownstream part and the upstream part can be arranged to be moved apartand moved together for the supply into the brewing chamber 200 and theevacuation from the brewing chamber 200 of the ingredient.

Typically, the upstream part of the brewing chamber 200 that isintegrated into the thermoblock 101, will be fixed in the beveragepreparation machine or coffee machine 104 and the downstream part of thebrewing chamber will be movable, or vice versa. The brewing chamber 200may have a generally horizontal orientation, i.e. such a configurationand orientation that the water flows through the in the brewing chamber200 along a generally horizontal direction, and the upstream part and/ordownstream part may be movable in the same or in the opposite directionof the water flow in the chamber. Embodiments of such a thermoblock andbrewing chamber are for example disclosed in WO 2009/043630, the contentof which is hereby incorporated by way of reference.

Controller 2 is secured to metal mass 1 via snaps 3A of housing 3 thatcooperate with corresponding recesses 1A in the surface of metal mass 1when housing 3 is assembled to metal mass 1 in the direction of arrow300.

The two part housing 3 of controller 2 encloses a printed circuit board4 said PCB on all sides, in particular in a substantially imperviousmanner so as to protect the PCB 4 against liquid and vapours in themachine. This PCB 4 is shown on FIG. 1 by transparency. The two parts ofhousing 3 may be assembled by screws 3B or any other appropriateassembly means, such as rivets, gluing, welding, or the same. Controller2 includes a user interface with a master switch 2A and two controlswitches 2B that are connected via housing 3 to the PCB. It is of coursepossible to use more elaborated user interfaces including screens ortouch screens. The PCB 4 includes power connectors for supplyingelectric heating power to metal mass 1 via power pins 11 extendingthrough corresponding openings in housing 3, further electricalconnectors for one or more further electric devices of the beveragepreparation machine, such as a user interface, pump, fan, valve,sensors, or the same, as required, and a connector to the mains for thecentral electric power supply.

The thermoblock 101 receives electric components, namely at least onetemperature sensor 70 connected to the PCB 4, a thermal fuses 75, apower switch in the form of a triac 60 in a cavity the opening of whichis formed between protruding walls 102 and a heating resistor not shownon the figures with connector pins 11, that are rigidly secured intometal mass 1 and rigidly connected to the PCB 4. Furthermore, the PCB 4is electrically connected via a rigid connector or cable 91 to a hallsensor 90 of a flowmeter that is located on the water circuit of thebeverage preparation machine, typically between a pump and a water orother liquid source such as a water or liquid reservoir, or between apump and a thermal conditioning device 100, or within the thermalconditioning device 100.

Moreover, the PCB 4 may carry a micro-controller or processor andpossibly a clock 30, preferably a quartz clock, for controlling theintensity of current passed to resistive heating element based on theflow rate of the circulating water measured with the flow meter and thetemperature of the heated water measured with the temperature sensor 70.Sensor 70 may be located within the thermoblock at a distance from thecirculating water so as to provide an indirect measure of the watertemperature. To increase the accuracy of the temperature control, one ormore temperature sensors 70 may be incorporated into metal mass 1 and/orinto the brewing chamber 200 and/or upstream the metal mass 1 or at itswater inlet. The controller or processor may also control furtherfunctions of the liquid food or beverage preparation machine, such as apump, a liquid level detector in a water supply reservoir, a valve, auser interface, a power management arrangement, an automatic beverageingredient supplier such as an integrated coffee grinder or an automaticsupplier of ingredient capsules or pods, or the same.

Further details of the heating device and its integration in a beveragepreparation machine are for example disclosed in WO2009/043630, WO2009/043851, WO 2009/043865 and WO 2009/130099, the contents of whichare hereby incorporated by way of reference.

Hereafter is presented a detailed example of a start-up profile of acontroller 2, with a preferred associated method of control, in order touse the controller 2 as a self-learning controller, and in order to usethe thermal conditioning device 100 as a self-learning thermalconditioning device.

This start-up profile and this method are arranged in order to optimizethe heating up of such a thermal conditioning device 100 for a beveragepreparation machine, particularly a coffee machine 104, in which liquidis circulated through a thermoblock 101 and then guided into a brewingchamber 200 for brewing a beverage ingredient supplied into the brewingchamber 200.

More particularly the invention concerns such a thermal conditioningdevice 100 including at least such a self-learning controller 2,arranged to be used as a self-learning thermal conditioning device andarranged to be incorporated into such a beverage preparation machine,e.g. a coffee machine 104, which can each include a plurality of suchthermal conditioning devices 100, for example for differentpreparations.

This self-learning controller 2 comprises:

-   -   at least one temperature sensor 70 connected or integrated to        the controller 2; and    -   at least one clock 30 to launch measures of temperature Ti at        periodic time intervals ti.

Preferably it also includes:

-   -   data storage means 105 for storing a target temperature TT,        which is in the case of a coffee machine the actual operative        temperature to make coffee, and said measured temperatures Ti ad        said periodic time intervals ti; and    -   calculation means 107 for calculating a switch-off temperature        SOT.

According the invention these said calculation means 107 are arrangedfor:

-   -   a) calculating temperature gradients Gi between different stored        temperatures Ti values;    -   b) calculating an average gradient AG of said temperature        gradients Gi; and    -   c) calculating a switch-off temperature SOT by subtracting an        overshoot temperature OS to said target temperature TT, said        overshoot temperature OS corresponding to said average gradient        AG by means of a calculation or a correlation. This overshoot        depends on the thermic inertia of the installation.

The start-up profile of the controller 2 allows reaching the optimaloperative temperature. In a preferred manner this operative temperatureis equal to this switch-off temperature SOT.

According the invention said storage means 105 are further arranged forstoring one or more of following parameters, and preferably all of them:

-   -   A) said calculated or correlated overshoot temperature OS;    -   B) said calculated temperature gradients Gi;    -   C) said calculated average gradient AG; and    -   D) said calculated switch-off temperature SOT.

Said self-learning controller device 2 is arranged for switching offsaid thermal conditioning device 100 when the last measured temperatureTi overshoots said calculated switch-off temperature SOT.

In an embodiment, said data storage means 105 store conversion tables108 between said average gradients AG and overshoot temperatures OS, andin that the value of overshoot temperature OS corresponding to the lastcalculated average gradient AG is extracted from said conversion tablesby said calculation means 107.

In another embodiment, said calculation means 107 calculate said valueof overshoot temperature OS from said last calculated average gradientAG.

This self-learning controller 2 enables the working of a process methodfor optimized heating up of the thermal conditioning device 100, tooperating temperature from any starting temperature or temperature ofinactivity TI with best possible heat up time.

The method of optimized heating up of such a thermal conditioning device100 for a beverage preparation machine, such as a coffee machine 104, tooperating temperature from any starting temperature with best possibleheat up time, includes the following steps:

-   -   a) said clock 30 triggers at each time interval a measure of        temperature Ti;    -   b) said measured temperatures Ti are stored one after another in        a stack memory 106 included in said data storage means 105;    -   c) said calculation means 107 calculate temperature gradients Gi        between some of said stored temperatures Ti values;    -   d) said calculation means 107 calculate an average gradient AG        of said temperature gradients Gi;    -   e) said calculation means 107 calculate a switch-off temperature        SOT by subtracting an overshoot temperature OS to said target        temperature TT, said overshoot temperature OS corresponding to        said average gradient AG by means of a calculation or a        correlation; and    -   f) said controller 2 device switches off said thermal        conditioning device 100 when the last measured temperature        overshoots said calculated switch-off temperature SOT.

Preferably said storage means 105 still store:

-   -   said calculated or correlated overshoot temperature OS;    -   said calculated temperature gradients Gi; and    -   and said calculated average gradient AG, and said calculated        switch-off temperature SOT.

Said data storage means 105 may include a stack memory 106 for storing agiven number N of successive measured temperatures Ti corresponding to agiven duration D, each new measured temperature Ti controlled by saidclock 30 being stored in said stack memory 106 while the oldest measuredtemperature being eliminated from said stack memory 106.

In an embodiment, said calculation means 107 calculate each temperaturegradient Gi between stored measured temperatures Ti which are spacedfrom each other of half of said given duration D, each new calculatedtemperature gradient Gi being stored in said stack memory 106 while theoldest calculated gradient being eliminated from said stack memory 106.

Said given number N of successive measured temperatures Ti stored may bean even number, and the number of stored temperature gradients Gi can beequal to half of said even number N.

In the following and not limitative example this given number N is setto 8, the period of time, i.e. time interval, between two followingtemperature measures is 0.5 sec, and the supervision of heat-up of theheater is a duration D of 4 gliding seconds. The number n of calculatedtemperature gradients is 4.

In order to determine the value of the overshoot temperature OS two waysare possible:

-   -   either said data storage means 105 store conversion tables 108        between said average gradients AG and overshoot temperatures OT,        and the value of overshoot temperature OT corresponding to the        last calculated average gradient AG is extracted from said        conversion tables 108 by said calculation means 107,    -   or said calculation means 107 calculate said value of overshoot        temperature OT from said last calculated average gradient AG.

In an embodiment, said controller 2 implements a software, preferablydedicated to the thermal conditioning device 100 concerned, saidsoftware managing the heat up cycle of a thermal conditioning device 100of the coffee machine 104 or similar, said software is using a systemindex that is written and stored to a permanent memory, e.g. EEPROM.

Preferably the PCB 4 contains said data storage means 105, said stackmemory 106, said calculation means 107, said conversion tables 108, andsaid software.

Upon factory delivery this index is set to average environmental andtechnical constellations.

With each heat up this index is re-calculated and if it fulfils certaincriteria it is written to the permanent memory. That means the old indexis overwritten by the new index.

Such criteria that need to be fulfilled to overwrite the old indexinclude:

-   -   how constant is the gradient of the temperature rise, e.g. less        than 5% fluctuation over 5 sec.    -   temperature at the start of the heat up must be below a certain        value, e.g. below 30 or 40° C.

The environment and certain technical constellations influence the timeneeded to heat up the coffee machine. Such constellations include:

-   -   net voltage tolerances, for example tolerances from nominal        voltage up to +/−20%    -   heat resistance tolerances of heater element in thermoblock, for        example +/−10%    -   different environmental temperatures, for example 5° C. to 40°        C.    -   different thermal isolation of heater, which entails different        temperature losses, for example +/−5%    -   different heater starting temperatures, for example 5° C. to 90°        C.    -   heater either full of water or empty.

The system index is characterizing the gradient of the temperature riseduring the heat up of the coffee machine 104. This index is depending onthe following system parameters, linked to the environmental/technicalconstellations described above:

-   -   effective net voltage    -   effective heat resistance    -   effective temperature sensor characteristic    -   current environmental temperature    -   effective energy loss of heater, particularly energy fluctuation        due to isolation, position in machine    -   current heater starting temperature, from 5° C. to 90° C.    -   heater filled with water or empty.

As the index is re-calculated with each new heat up, it is changing.Originally, according to a factory setting, the index is set to an“average environment”. With the repeated recalculation according theinvention the index is adjusted to the actual environment the machine isoperated in and the technical characteristics of the components builtinto the specific machine the index is calculated for. The constantre-calculation of the index allows also the adaption to changingconditions, e.g. seasonal changes, location changes, or similar.

As the index is optimized to its environment it allows in the softwareof the coffee machine 104 the definition of the needed energy, duringthe time the heater is switched on, to drive the heater to the targettemperature TT with one single and well defined pulse in the bestpossible heat up time. It allows obtaining physically absolute best casefor the heat up time.

The machine takes the last stored index number from the EEPROM andcalculates the needed time the heater is switched on to reach the targettemperature based on the index from the permanent memory.

The starting point for the first coffee brewing can be defined in threepossible ways:

-   -   in a first way, heat up the system with one energy shot from any        starting temperature, and wait with the release of the brewing        mode until the temperature sensor reaches target brewing        temperature. Indicate brewing mode ready with any signal for the        user, typically done with a LED signal or the same.    -   in a second way, heat up the system with one energy shot from        any starting temperature, and release the brewing mode as soon        as this energy shot is done. The energy is already in the        system, but the temperature sensor, due to thermal inertia, has        still not reached target temperature. The correction for this        thermal inertia delay will be made by using a different        temperature regulation for the first cup after heating. This        different regulation of the first cup brewing depends to the        time delay between this shot energy batch is finished and the        first cup is started by the user. Typically this delay varies        between 0 sec. and approximately 15 sec., after 15 sec. the        thermal inertia of the system is balanced and the system is        equal to status one and ready for standard brewing.    -   in a third way heat up the system with one energy shot from any        starting temperature, the user presses a coffee button during        one shot heat up, and the pump will start as soon as this energy        shot is done. Therefore the first cup regulation is as written        in the second way with a delay of 0 sec.

The brewing mode, or more generally the beverage preparation mode,includes the circulation of fluid, e.g. water, through the thermaldevice, e.g. heater, once the thermal conditioning device is thermallyready for bringing to the target temperature the fluid circulatingtherethrough for preparing a beverage, e.g. coffee, with the desiredproperties, e.g. temperature and/or brewing characteristics.

In detail of FIG. 3, the heat-up curve can be classified in threetypical areas: a first area A “heat-up start”, a second area B “lineartemperature gradient” and a third area C “heat-up engage”.

In the first area A “start heat-up” the change of temperature gradientis very extreme. This first area is not useable for calculating aconstant gradient of temperature.

The second area B “linear temperature gradient” is the important area tocalculate the temperature gradient.

After switching off the heater, the third area C “engage area” begins.Here engages the temperature from the temperature SOT switch offtemperature, where the heater is switched off to the target temperatureTT. This target temperature TT can be a parameter of the machine, forexample with the maximal value of 96° C. for a coffee machine: in avariant the user can set it, for example with a button or the same.

The gradient of temperature can be calculated from heat up start untilthe end of the “linear temperature gradient” sequence. After leavingthis temperature area, the gradient of temperature is frozen to the lastcalculated value. For example, the last 4 seconds of gradientcalculation are considered and stored to the machine EEPROM.

In the fast heat-up mode the temperatures of the thermoblock are storedin an array of N samples in discrete time steps of D/N sec., e.g. 8samples in discrete time steps of 0.5 sec. In this array the average ofthe last D, e.g. 4, measured seconds is always available.

After every periodic step of D/N sec, e.g. 0.5 sec., the oldesttemperature is deleted, which corresponds to the temperature at a timeof D, e.g. 4 sec., before the present instant, and a new temperature isstored. Thereafter, the calculating process may start again.

In fast heat-up mode, for every time step of D/N, e.g. 0.5 sec., atemperature gradient is calculated from these values.

The algorithm of acquiring the temperature gradient can be the followingin the case of N=8:

Temperature values T1 to TN can be stored in an array as here described,assuming a later temperature is higher than the previous temperature. Ata given point of time (t=0), the array will contain the followingprevious acquired (e.g. measured and/or derived) and stored temperaturevalues:T1=temperature (t=−0.5 sec)T2=temperature (t=−1 sec),T3=temperature (t=−1.5 sec),T4=temperature (t=−2 sec),T5=temperature (t=−2.5 sec),T6=temperature (t=−3 sec),T7=temperature (t=−3.5 sec),T8=temperature (t=−4 sec),

From these values the average temperature gradient AG can be calculatedas follows, after the calculation of the n temperature gradients G_(i),from G₁ to G_(n), e.g. n=N/2=4

G1=Gradient 1=T1-T5=temperature (t=−0.5 sec)−temperature (t=−2.5 sec);

G2=Gradient 2=T2-T6=temperature (t=−1 sec)−temperature (t=−3 sec);

G3=Gradient 3=T3-T7=temperature (t=−1.5 sec)−temperature (t=−3.5 sec);

G4=Gradient 4=T4-T8=temperature (t=−2 sec)−temperature (t=−4 sec).Consecutively an average temperature gradient AG is built by averagingthe 4 gradients mathematically: AG=1/n. Σ_(i=1) ^(n) with n=N/2 In thisexample, AG=¼(G1+G2+G3+G4).

A definition of the overshoot temperature OS after switching the heateroff may be the following: the overshoot temperature OS of a thermoblocksystem depends on all relevant physical influences like gradient ofheating temperature course, mass of the thermoblock, mass of thefilling, namely with water, in the thermoblock and can be calculated ordetermined experimentally.

The average gradient of temperature AG can now be allocated to onespecific overshoot OS temperature.

The switch off heater temperature SOT of the heater is calculated ordetermined by using a conversion table 108 for example as following:

AG = Gradient 7 8 9 10 11 12 (° C./sec) OS = Overshoot (° C.) 8 10 11 1213 13SOT=Switch off heater temperature=TT−OSSOT=Target temperature heatup−Overshoot temperatureAG=1/n. Σ_(i=1) ^(N)G_(i) n=N/2

A cold heat up can be defined as a heat up process that starts with aheater temperature below a threshold temperature, e.g. 50° C. Duringsuch a heat up the above mentioned determination of the temperaturegradient is possible and each time done. In this case, the machine worksalready in the current heat up with the simultaneously elaboratedgradient.

A warm heat up occurs as soon as the machine has to be heated up whenthe heater is already above this threshold temperature, e.g. 50° C. Thenthe system is not able to determine the temperature gradient and thusthe last stored number in the EEPROM will be considered for defining theovershoot temperature.

The improvements and advantages achieved by the invention include a selfcalibrating system to optimize heat up time, working with optimal heatup time from every heater starting temperature, any heater powertolerance, network voltage tolerance, water in thermoblock, heaterenergy loss and environmental temperature.

Additionally, the first cup of beverage can be prepared after a coldstart up in three possible modes:

-   -   A) based on the temperature measured, after one single energy        shot is sent through the heating device and the thermal inertia        of the system is balanced    -   B) based on the calculated energy batch of one single energy        shot and the delay between end of heating up and starting first        cup    -   C) on request by a user, while the heat up algorithm of one        single energy shot is carried out, the beverage preparation        being carried out without delay automatically thereafter.

The selection of these modes A, B, C, can be made by the user with aselection button or by the controller itself.

The logic diagram of FIG. 4 shows an example of the sequence of steps tobuild a software for the control of heating up according to theinvention:

-   step 110: power on-   optional variant step 11: choose target temperature TT?    -   If yes, step 12 input value of TT    -   If no, step 13 call memory, and validate the last TT-   optional variant step 115: choose mode A,B,C?    -   If yes, step 116 select chosen mode    -   If no, step 117 call memory, and validate the last mode-   step 120: reset time counter to zero and start the clock-   step 130: measure heater temperature HT-   step 140: HT greater as 50° C.?    -   If no, step 150    -   If yes, step 160-   step 150: determination of temperature gradient G at each time and    current heat up-   step 160: system not able to determine the temperature gradient-   step 170: read last stored number of average gradient AG in the    EEPROM-   step 180: take it as overshoot temperature OS-   step 190: start heat up-   step 1100: heat up-   step 1110: measure time-   step 1120: +D/N sec. ?    -   If no, return to step 1100    -   If yes, step 1130-   step 1130: store last value of current temperature CT-   step 1140: number of values=N?    -   If no, return to step 1100    -   If yes, step 1150-   step 150: store temperature value-   step 160: delete Nth oldest value-   variant step 1161: calculation of difference between (last value of    current temperature LVCT)−(penultimate value of current temperature    PVCT)    -   Step 1162: LVCT−PVCT greater as zero?        -   If yes, step 1163 continue, go to step 1170        -   If no, step 1164 alarm, and step 1165 power off-   step 1170: calculation of temperature gradients G_(i)-   step 1180: calculation of average gradient AG-   step 1190: determination of overshoot OS    -   Variant instead step 1190: step 1195 calculation of overshoot OS-   step 1200: calculation of the switch-off temperature SOT=TT−OS-   step 1210: current temperature CT greater as SOT?    -   If no return to step 1100    -   If yes, step 1220 switch off heater-   step 1230: store last average gradient AG-   step 1240: current temperature=TT?    -   If no, step 1241 wait, and return step 1240    -   If yes, step 1250 ready to prepare beverage to user.

This logic diagram is an example. It will be apparent to the skilledperson that other sequences allow the realization of the invention.

An advantage of the invention lies in a very fast heat up time, combinedwith an immediate release of the brewing mode, which saves time, and thepossibility of a semi-automatic start of first cup brewing. This heatingdevice is a self-learning heating device and its utilisation is veryeasy for the user.

The invention claimed is:
 1. A unit for controlling transmission ofpower to a thermal conditioning device, the unit comprising: acontroller with a start-up profile for starting-up such a thermalconditioning device from a temperature of inactivity to an operativetemperature for bringing to a preheating target temperature a fluidcirculating through the thermal conditioning device at start-up end; atemperature sensor connected to the controller for determining atemperature of the fluid upon circulation through the thermalconditioning device; the controller being arranged to allow circulationof fluid through the thermal conditioning device at the end of start-upand to compare the determined temperature of fluid circulated at the endof start-up to the preheating target temperature and derive atemperature difference therefrom, the controller including (1) at leasta clock to launch measures of temperature at periodic time intervals,(2) data storage for storing the preheating target temperature and forstoring temperatures measured at the periodic time intervals, and (3) acalculator that calculates a switch-off temperature, temperaturegradients between different stored temperatures values, an averagegradient of the temperature gradients, and a switch-off temperature bysubtracting an overshoot temperature from the preheating targettemperature, the overshoot temperature corresponding to the averagegradient by calculation from the last calculated average gradient, or bya correlation with stored conversion tables between the averagegradients and overshoot temperatures, wherein the data storage storesthe overshoot temperature, the calculated temperature gradients, thecalculated average gradient, and the calculated switch-off temperature,and wherein the controller is arranged for switching off the thermalconditioning device when the last measured temperature overshoots thecalculated switch-off temperature; and the start-up profile has at leastone parameter and the controller has a self-learning mode for adjustingthe at least one parameter as a function of the temperature differenceand to store the adjusted parameter for a subsequent starting-up of thethermal device.
 2. The unit of claim 1, wherein the parameter is aduration of the power start-up profile.
 3. The unit of claim 1, whereinthe parameter is a power intensity of the power start-up profile.
 4. Theunit of claim 1, wherein the parameter is the preheating targettemperature of the thermal conditioning device.
 5. The unit of claim 1,wherein the thermal conditioning device has a thermal accumulator or athermoblock.
 6. The unit of claim 1, wherein the data storage includes astack memory for storing a given number of successive measuredtemperatures corresponding to a given duration, and each new measuredtemperature controlled by the clock being stored in the stack memorywhile the oldest measured temperature is eliminated from the stackmemory, and wherein the calculator calculates each temperature gradientbetween stored measured temperatures which are spaced from each by halfof the given duration, each new calculated temperature gradient beingstored in the stack memory while the oldest calculated temperaturegradient being eliminated from the stack memory.